Circuit Simulation Project
8 to 3 bit Priority Encoder
Submitted by: Mohammad Khalique Khan
Aliah University, Kolkata – India
Introduction
An encoder is a kind of combinational circuit which converts multiple input
signal to a coded output signal in such a way that the output signal reassembles
complete information which is fed at the input of the encoder. The encoder
consists of ‘2n’ bits of input lines and ‘n’ bits output lines. The circuit of an
encoder is based on the operation of Boolean expressions.
8 to 3-bit priority encoder is an encoder that consists of 8 input lines and 3
output lines. It can also be called an Octal to a binary encoder. Each input line
has a base value of 8 (octal) and each output has a base value of 2 (binary).
The truth table below gives us an idea of the operation of the 8 to 3-bit Priority
Encoder.
Inputs
Outputs
D7
D6
D5
D4
D3
D2
D1
D0
Q2
Q1
Q0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
X
0
0
1
0
0
0
0
0
1
X
X
0
1
0
0
0
0
0
1
X
X
X
0
1
1
0
0
0
1
X
X
X
X
1
0
0
0
0
1
X
X
X
X
X
1
0
1
0
1
X
X
X
X
X
X
1
1
0
1
X
X
X
X
X
X
X
1
1
1
Logical Expression for Output lines
Q0 = D1 + D3 + D5 + D7
